Siemens 6SE7090-0XX84-0FB0 SBR1 Resolver Encoder Board

SIMOVERT MASTERDRIVES Motion Control | Measuring Value Encoder Module | Resolver Evaluation Without Pulse Encoder Simulation | Slot C (Option C23)

The Board That Closes the Resolver Feedback Loop

Inside a SIMOVERT MASTERDRIVES Motion Control drive, position and speed data flows back from the motor through a carefully matched chain of hardware. When the motor uses a resolver as its feedback device — which remains one of the most mechanically robust and environmentally tolerant sensing technologies available — that signal needs a dedicated evaluation board to translate analog resolver signals into the digital feedback the drive's control electronics can process.

The 6SE7090-0XX84-0FB0 is that board. Designated SBR1 within the MASTERDRIVES option catalog, it is the measuring value encoder module for resolver evaluation without incremental encoder simulation. It installs directly into slot C of SIMOVERT MASTERDRIVES compact and chassis units, assigned as option code C23, and handles the full resolver-to-drive signal conversion that makes closed-loop motor control possible in machines equipped with resolver-fitted servo motors.

Product Specifications

What a Resolver Is and Why It Gets Its Own Evaluation Board

A resolver is a rotary electrical transformer mounted on a motor shaft. As the shaft rotates, it generates two analog output signals — a sine and a cosine — whose amplitude varies with angular position. Unlike optical encoders, resolvers contain no active electronics, no glass discs, no semiconductor emitters. They're fundamentally passive devices, which is exactly why they survive heat, vibration, contamination, and shock that would destroy optical encoder systems.

The tradeoff is that the resolver's raw analog output is not something a digital drive controller can use directly. That's the job the SBR1 board performs: it receives the resolver excitation signal, accepts the sine and cosine feedback, and performs the mathematical conversion — Resolver-to-Digital (R/D) — that produces the angular position and velocity data the MASTERDRIVES Motion Control firmware needs to run the closed-loop current, speed, and position control loops.

Without a correctly functioning SBR1 in slot C, a MASTERDRIVES unit configured for resolver-equipped motors simply cannot operate. The drive will fault on startup with an encoder evaluation error, and no motor movement is possible until the board is replaced and the resolver interface restored.

SBR1 vs. SBR2: Knowing Which Variant Your System Uses

The MASTERDRIVES Motion Control catalog offers two resolver evaluation boards, and selecting the wrong one for a replacement will cause compatibility problems:

SBR1 (6SE7090-0XX84-0FB0) — Option C23: Evaluates the resolver signal and delivers position and velocity data to the drive's internal control loops. Does not provide simulated incremental encoder output on external terminals. This is the correct board for systems where the resolver feedback is used exclusively by the MASTERDRIVES drive and no external device (PLC, CNC, position display) needs a pulse train derived from the resolver signal.

SBR2 (6SE7090-0XX84-0FC0) — Option C33: Adds an incremental encoder simulation output on top of the resolver evaluation. This allows external systems to receive a conventional A/B pulse train representing motor position, derived from the resolver signal, without needing a separate physical encoder. Used in machines where a higher-level controller or a position display needs position feedback from the motor axis.

Before ordering a replacement, confirm which option code is recorded in the machine's documentation or visible on the board installed in slot C. Substituting SBR2 for SBR1 will not cause damage, but the extra simulation output will go unused, and the drive software parameters must be correctly configured to match the installed board variant.

Installation Context: Where This Board Lives in the Drive

The SIMOVERT MASTERDRIVES compact and chassis unit architecture uses a modular option board approach. The base unit contains the power electronics and core control circuitry, while application-specific functionality — encoder interfaces, communication protocols, expansion I/O — is added via boards that plug into dedicated internal slots labeled A through G.

The SBR1 board occupies slot C, which is designated for the motor encoder board in all compact and chassis unit configurations. The board connects to the resolver via the drive's standard encoder connector on the front or side panel, and communicates with the main control board over the internal slot bus. There is no external wiring to the board itself beyond the resolver cable that routes through the drive's standard encoder input terminals.

The MASTERDRIVES Motion Control platform this board supports has been widely deployed in machine tools, printing presses, winding machines, test stands, and multi-axis coordinated systems built around Siemens servo motors with resolver feedback — typically the 1FT5 and 1FT6 motor families, among others.

Sourcing a Replacement: Spare Part and Retrofit Kit Options

Two procurement routes exist for this board. The 6SE7090-0XX84-0FB0 is the spare part designation — a single board supplied ready to drop into an existing slot C that previously held an SBR1. The 6SX7010-0FB00 is the retrofit kit designation, which includes the board plus the mounting hardware and cable accessories needed to add this option to a unit that was not originally delivered with resolver evaluation capability.

For a like-for-like replacement in a system that already has an SBR1 installed, the spare part number is the correct reference. The retrofit kit is the appropriate choice only when adding resolver evaluation capability to a MASTERDRIVES unit that was originally configured without it.

Frequently Asked Questions

Q1: Can the 6SE7090-0XX84-0FB0 be used in both compact and chassis versions of SIMOVERT MASTERDRIVES?

Yes. Siemens' MASTERDRIVES ordering documentation confirms the SBR1 board plugs into slot C across both compact unit and chassis unit configurations. The board and slot interface are common across the product family, so a single spare covers both form factors.

Q2: The board is listed as discontinued — does that mean the drive itself is also out of support?

The SBR1 board has been discontinued from standard Siemens production, but this reflects the lifecycle status of the MASTERDRIVES platform as a whole rather than the board specifically. SIMOVERT MASTERDRIVES units remain in active service on production machines globally, and the boards remain available through authorized industrial automation spare parts distributors and certified refurbishment channels. A discontinued status in Siemens' standard catalog does not mean the product has disappeared from the market.

Q3: What fault alarms in the MASTERDRIVES indicate a failed SBR1 board?

The most direct indicators are encoder evaluation faults on startup — the drive will typically display an alarm related to motor feedback signal absence or encoder hardware fault. Speed control instability, unexplained position drift, or complete failure to close the speed loop after drive enable can also result from a degraded resolver board. If the resolver cable and resolver itself have been verified as functional and the fault persists, the SBR1 board is the next component to suspect and replace.

Q4: Is any drive parameter change required after replacing the SBR1 board?

In a like-for-like replacement — same board variant (SBR1 for SBR1), same resolver motor — no parameter changes are typically necessary if the drive's parameters have been correctly set for resolver operation before the failure. However, after any board replacement, it is good practice to verify that the encoder type parameter (P130 in MASTERDRIVES firmware) is correctly set for resolver operation, and to perform a resolver offset calibration if the new board or installation introduces any offset. Consult the MASTERDRIVES commissioning documentation specific to your firmware version.

Q5: What is the difference between using the SBR1 with the MASTERDRIVES Motion Control variant versus the Vector Control variant?

The SBR1 board hardware is the same regardless of which drive firmware variant it's installed in. The difference lies in how the drive software uses the resolver data. In Motion Control variants, resolver feedback supports the full servo control loop including position control, enabling precise axis positioning. In Vector Control variants, resolver feedback typically supports speed control and may provide better low-speed performance than open-loop operation, but full position servo functionality depends on the firmware and configuration. Confirm the firmware variant of your drive before configuring resolver-based control modes.